1. Field of the Invention
This invention relates to magnetoresistive (MR) sensors and more particularly to MR sensor devices and methods of fabrication thereof.
2. Description of Related Art
Kim et al., U.S. Pat. No. 5,608,593 for xe2x80x9cShaped Spin Valve Type Magnetoresistive Transducer and Method for Fabricating the Same Incorporating Domain Stabilization Techniquexe2x80x9d shows a spin valve (SV) with a permanent magnet with a non-magnetic (e.g., Cr) underlayer (Separation layer). (See col. 5, lines 15 to 25.)
Ravipati, U.S. Pat. No. 5,709,358 for a xe2x80x9cSpin Valve Magnetoresistive Transducers Having Permanent Magnetsxe2x80x9d has thin film layers of ferromagnetic material separated from each other by a nonmagnetic spacer. The direction of magnetization of one thin ferromagnetic layers is pinned by a permanent magnetic layer. Another permanent magnetic layer is located adjacent to the other thin film layer to provide longitudinal biasing.
Mauri, U.S. Pat. No. 5,796,561 for a xe2x80x9cSelf-biased Spin Valve Sensorxe2x80x9d discloses a Spin Valve (SV) MagnetoResistive (MR) sensor with a free layer separated from a pinned layer by a spacer layer.
Takada et al., U.S. Pat. No. 5,828,527 for a xe2x80x9cThin Film Magnetic Head Having Magnetic Resistance Effect Stabilizing Layerxe2x80x9d describes a thin film magnetic head with a magnetoresistance effect stabilizing layer with an underlayer of Ta or oxides of Al or Si, a buffer layer of chromium (Cr), a separation layer of Cr or Ta and a hard magnetic layer.
A spin valve device comprises a free layer, a spacer layer, a pinned layer, an antiferromagnetic layer, and a patterned underlayer that includes a magnetic material for providing trackwidth and longitudinal bias. The patterned underlayer can comprises a buffer layer, an antiferromagnetic layer and a ferromagnetic layer. Alternatively, the patterned underlayer can comprises a buffer layer, a chromium layer and a magnetically hard, i.e. permanently magnetic, layer which provides trackwidth, longitudinal bias, and magnetic stabilization.
In accordance with this invention a continuous fee layer spin valve (SV) Sensor with a patterned exchange underlayer stabilization. The underlayer (antiferromagnet) is formed under the magnetically hard or permanently magnetic (PM) material.